feifei-120

120. In Europe, schoolchildren devote time during each school day to calisthenics. North American schools rarely offer a daily calisthenics program. Tests prove that North America children are weaker, slower, and shorter-winded than European children. We must conclude that North American children can be made physically fit only if they participate in school calisthenics on a daily basis.

Which one of the following is assumed in the passage?

(A) All children can be made physically fit by daily calisthenics.

(B) All children can be made equally physically fit by daily calisthenics.

(C) Superior physical fitness produces superior health.

(D) School calisthenics are an in indispensable factor in European children’s

(E) North American children can learn to eat a more nutritious diet as well as to exercise daily.

为啥答案是D呢，我觉得only if后面是必要条件吧，A也是说必要条件成立，想不通啊！！！